Mechanism for reducing unburned hydrocarbon emission



May 24, 1965 H. H. DIETRICH ETAI. 3,252,450

MECHANISM FOR REDUCNG UNBURNED HYDROCARBON EMISSION 13 Sheets-Sheet l Filed Oct. 18, 1963 DISTRIBUTOR :,mm 1 I I 'I eilig.'

May 24, 1966 H. H. DIETRICH ETAL.

MECHANISM FOR REDUCING UNBURNED HYDROCARBON EMISSION 5 Sheets-Shea??l 2 Filed OC'L. 18, 1963 May 24, 1966 H. H. DlETRlcn-l ETAL. 3,252,450

MECHANISM FOR REDUCING UNBURNED HYDROCARBON EMISSION 5 Sheets-Sheet 5 Fled Oct. 18, 1963 United States Patent O 3,252,450 MECHANISM FOR REDUClNG UNBURNED HYDRCARIBN EMISSION Howard H. Dietrich and Clarence I. Eckert, Rochester,

and Fred G. Michaels, Pittsford, N.Y., assignors to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Oct. 18, 1963, Ser. No. 317,199 4 Claims. (Cl. 12S-117) The present invention relates to a mechanism for reducing the amount of unburned hydrocarbon presently emitted from internal combustion spark ignition engines and is sepecically directed to a mechanism which opens the throttle valve slightly to provide a more combustible fuel mixture during deceleration of the engine. Since a high percentage of the unburned hydrocarbons emitted from such an engine are emitted vduring deceleration, the present invention accomplishes a considerable reduction in unburned hydrocarbon emission.

The present invention constitutes an improvement over the disclosure of United States Patent No. 3,027,884 issued in the names of M. E. Bale, Ir., and D. G. Guetersloh. The Bale and Guetersloh patent discloses a mechanism adapted to open the throttle valve and retard the spark in response to the high vacuum created during deceleration in the intake manifold of the engine. A more combustible fuel mixture is thereby provided duringV deceleration without transferring more power to the drive shaft. The several improvements of the present invention provide a mechanism more suitable for use in an automotive vehicle.

One of the difficulties encountered with the mechanisrns previously available is their tendency to actuate in response to the high manifold vacuum created during low speed, light load engine operation, particularly in an automobile traveling `slightly downhill. Such actuation is undesirable since the distributor, instead of increasing engine power through spark advance, Vcauses power absorption through spark retard. The present invention prevents such importune actuation by providing means to admit atmosphere to the vacuum operated mechanism whenever the throttle valve is held open by the normal foot pedal control. The admission of atmosphere prevents the vacuum from rising to the value at which the mechanism would actuate.

Another of the difficulties encountered with the mechanisms previously available is their tendency to cycle in response to its eiect on the the combustion process. That is, the mechanism, in response to high manifold vacuum, opens the throttle valve, thereby providing a more combustible fuel mixture, but yalso reducing the manifold vacuum. The mechanism then, in response to reduction of the manifold vaccum, closes the throttle valve, causing the manifold vacuum to increase. When the manifold vacuum reaches the value at which the mechanism actuates, the throttle valve is again opened, starting another cycle. The present invention prevents such cycling by providing means to admit atmosphere to the vacuum operated mechanism in response to closure of the throttle valve by the mechanism. The admission of atmosphere prevents the vacuum from increasing to the value at which the mechanism actuates, thereby preventing the mechanism from starting a second cycle.

A further diculty encountered with the mechanisms previously avail-able is their tendency to close the throttle valve very suddenly. A sudden closing of the throttle valve often causes stalling of an engine which is connected to an automatic transmission. The present invention incorporates in the mechanism a ball check valve which causes a gradual closing of the throttle valve.

The details as well as other objects and advantages of the present invention will be apparent from the accompanying description and the drawings in which:

FIGURE l is a View, partially in section with parts broken away, showing the mechanism mounted on a carburetor and schematically illustrating the connection to a distributor;

FIGURE 2 is `an enlarged sectional view of the valve mechanism, taken along lines 2-2 of FIGURES 1 and 3;

FIGURE 3 is an enlarged view of the valve mechanism, partially in section with parts broken away, taken along line 3 3 of FIGURE 1;

FIGURE 4 is an enlarged view partially in section with part broken away, showing the ball check valve included in the valve mechanism, taken along the lines 4-4 ot FIGURES 1 and 3;

FIGURE 5 is an exploded View of the lever arrangement show in FIGURE l; and y FIGURE 6 is a sectional view of an alternative embodiment of the valve mechanism shown in FIGURE 2, schematically illustrating the connections to a throttle valve and distributor.

Referring rst to FIGURE 1, the valve mechanism 10 is mounted on the carburetor 14 by a bracket 12. Hoses 16 and 18 connect valve mechanism 10 to servo mechanisms 20 and 22 which control the distributor 24.

The construction of distributor 24 may be that disclosed in the aforementioned Bale and Guetersloh patent. Generally speaking, valve mechanism 10 is designed to supply vacuum from the intake manifold of the engine (not shown) to either hose 16 or 18. When manifold vacuum is supplied through hose 16 to servo mechanism 20, distributor 24 advances the spark. When manifold vacuum is supplied through hose 18 to servo mechanism 22, distributor 24 retards the spark.

The construction of valve mechanism 10 is shown in FIGURE 2. A housing has a bore 102 in which a piston 104 is contained. Bore 102 is closed at one end by a threaded plug 106. A hose 26 provides an air flow conduit from a port 108 in housing 100 to the intake manifold. Passages 110 and 112 provide an air ow conduit between port 108 and a chamber 114 formed by more 102, the end of plug 106, and the face 116 of piston 104.

Manifold vacuum passes through port 108 and passages 110 and 112, enters chamber 114 and acts on face 116 of piston 104 against the force of a spring 11S. When the force of spring 118 is overcome, piston 104 moves to the right. The force of springf110 can be regulated by axial movement of threaded plug 106 in bore 102. Overtravel of piston 104 can be prevented by axial movement of a stud 120 threaded through plug 106.

While piston 104 remains in the position shown, passages 122 and 110 provide an air ow conduit to port 108 from an annular chamber 124 formed between piston 104 and bore 102. Passages 126 and 128 provide an air tlow conduit through piston 104 to annular chamber 124 from a chamber r1?0 formed by bore 102, the face 132 of piston 104, and a plug 134 closing the end of bore 102. A projection 136 on plug 134 v'spacesface 132 of piston 104 from plug 134. v A vent 138 admits atmosphere to chamber 130.

Manifold vacuum passes through port 108, passages 110 and 122, annular chamber 124,`and passages 126 and 128, enters chamber and combines with the atmosphere entering through vent 138 to produce a subatmospheric pressure in chamber 130. The value of the subatmospheric pressure may be regulated by the relative sizes of restrictions 140 and 142 located in passage 128 and vent 138, respectively. They subatmospheric pressure acts on face 132 of piston 104, complementing the force of spring 3 of spring 118 and resisting the movement of piston 104 toward the right.

When the manifold vacuum becomes sufficiently high to overcome the force of the subatmospheric pressure in chamber 130 and the force of spring 118, piston 104 moves to the right and interrupts the air 'flow from annular chamber 124 to passage 122. Therefore, air can no longer flow from chamber v130, and the pressure therein becomes atmospheric. Atmospheric pressure in chamber 130 provides less resistance to movement of piston 104 toward the right and, conversely, more resistance to movement of piston 104 toward the left. Thus, the manifold vacuum required to move piston 104 to the right being greater than that existing when piston 104 returns to the position shown by a predetermined increment, a differential pressure piston is provided which operates as a valve as described below.

While piston 104 remains in the position shown, passages 144 and 110 provide an air ow conduit to port 108 from an annular chamber 146 formed between piston 104 and bore 102. A port 148 in housing 100 provides an air flow conduit between annular lchamber 146 and hose 16. Manifold vacuum passes through port 108, passages 110 and 144, annular chamber 146, port 148, and hose 16 and enters servo mechanism 20 which -then causes distributor 24 to advance the spark.

Also, while piston 104 remains in the position shown, a

vent 154 admits atmosphere to an annular chamber 150 formed between piston 104 and 'bore 102. A port 152 in housing 100 provides `an air flow conduit between annular chamber 150 and hose 18. Atmosphere passes through vent 154, annular'chamber 150, port 152, and hose 18 and enters servo Amechanism 22 which then causes distributor 24 to advance the spark.

When high manifold vacuum moves -piston 104 to the right, the flow of atmosphere into chamber 150 is interrupted.- Instead, passages 122 and 110 provide an air flow conduit to port 108' from `annular chamber 150. Manifold vacuum passes through port 108, passages 110 and 122, annular chamber 150, port 152, and hose 18 and enters servo mechanism 22 which then 'causes distributor 24 to retard the spark.

Also, when high manifold vacuum moves piston 104 to the right, air How from annular chamber 146 to passage 144 is interrupted. Instead, vent 154 admits atmosphere -to annular chamber 146. Atmosphere passes through vent 154, annular chamber 146, port 148, and hose 16 and enters servo mechanism 20 which then causes distributor 24 to retard the spark.

Piston 104 thus operates as a valve, supplying manifold vacuum to servo'mechanism 20 and atmosphere to servo mechanism 22 and advancing the spark when manifold vacuum is low and supplying vacuum to servo mechanism 22 and atmosphere to servo mechanism 20 and retarding the spark when manifold vacuum is high.

Also, when high manifold vacuum moves piston104 to the right, an annular chamber 156, formed between piston 104 and bore 122, slides adjacent passage 144 to prevent the manifold vacuum present in passage 144 from causing piston 104 to bind in bore 102. i i

Referring to FIGURE 4, passages 158, 160, and 170 provide an air flow conduit between annular chamber 150 and a chamber 172. Located in passage 160 is a ball 'checkvalve 162, the seat 164 of which is nicked, as'at 166. Air ow downward through Avalve 162 is unimpeded, whereas air ow upward throughvalve 162 is restricted to pass through nick 166 in seat 164.

Passage A160 is open at one end to the atmosphere. The flow of atmosphere through passages 160 and 170 into chamber 172 is limited by a restriction 168 located in the end of passage 160.

Referring again to FIGURE 2, chamber `172 is formed by clamping a flexible diaphragm 174 over the end of housing 100. Aspring 176 biases diaphragm 174 toward the right, against lthe force 0f `the `throttle return spring (not shown).

When high manifold vacuum moves piston 104 to the right, manifold vacuum passes through po'r't 108, passages 110 and 122, annular .chamber 150, and passages 158, 160, and 170, enters chamber 172 and combines with the atmosphere entering through passages 160 and 170 to produce a subatmospheric pressure, pulling diaphragm 174 toward the right to the position indicated by outline 177.

When the manifold vacuum reduces and piston 104 returns to the position shown, atmosphere enters chamber 172 both through the open end of passage 160 and passage 170 and through vent 154, annular chamber 150, and passages 158, 160, and 170. The ovv of atmosphere upward" through passage 160, it will be remembered, is restricted to pass through nick 166 in seat 164 of ball check valve 162. The flow of atmosphere into chamber 172 is slowed, therefore, by valve 162 and restriction 168, and diaphragm 174 will return gradually to the position shown.

Secured to diaphragm 174 is a plunger 178 in 'which is threadedly received a stud 28. As Shown in FIGURE 5, stud 28 is slidably received through a hole in 'a bracket 30 which is rotatably connected by a pin 32 to a lever 34. Lever 34 is rotatably mounted on the throttle valve shaft 36. When diaphragm 174 is pulled by high manifold vacuum toward the right, stud 28 and bracket`30 move with it, rotating lever 34 clockwise about shaftA 36. A tang 38 on lever 34 engages a lever 40, secured to shaft 36, and causes lever 40 and shaft 36 to also rotate clockwise. wise rotation of shaft 36 opens the throttle valve (not shown). The throttle valve is thus opened in response to high manifold vacuum.

The throttle valve may also be opened by the normal foot pedal control (not shown) acting through a rod (not shown) to cause clockwise rotation of a throttle lever 42. Throttle lever 42 then engages a tang 44 on lever 40 and causes a clockwise rotation of lever 40 and shaft 36, thus opening the throttle valve.

When the foot pedal control causes counterclockwise rotation of throttle lever 42 away from tang 44 of lever 40, lever 40 and shaft 36 are rotated counterclockwise by a spring 46, and the throttle valve closes. Similarly, as diaphragm 174, plunger 178, and stud 28 move toward the left, the pressure brought by lever 34 through tang 38 against lever 40 is relieved, and spring -464 rotates lever 40 and shaft 36 counterclockwise, closing the throt- A pressure responsive piston 56 is located within cylinder 54. When high manifold vacuum moves piston I104 to the right, manifold vacuum passes through rport 108, passages and 122, annular chamber 150, port 152, and hose 52 to cylinder 54. Piston 56 is pulled toward the right and cocks a cam 58, rotatably mounted on bracket 12 by a pin 59 and riding loosely on a rod 60 secured to piston 56, into the position indicated by outline 61 in FIGURE 5.

When the manifold vacuum reduces and diaphragm 174 moves toward the left, spring 46 rotates levers 40 and 34 countercloekwise. Lever 34 engages a 'tang '64 on cam 58 in its cocked position'61 and rotates cam 58 further clockwise into the position indicated by outline 63.

In position 63, a tang 62 on cam V58 depresses a lever arm 6 6 ofA an inlet 68 mounted on bracket 12 as shown in FIGURE l, thereby opening a stopper valve 70 to permit atmosphere to pass through inlet 68 and a hose,

The clockconnection 72. Hose connection 72 connects with a hose 74 (not shown completely for the sake of clarity).

Hose 74 is connected to hose 26 leading from the intake manifold. Atmosphere present in hose 74 therefore ows to the intake manifold and to chamber 114 in valve mechanism 16 and causes a reduction in the value of the manifold vacuum. inasmuch as the atmosphere enters hose '74 concurrently with the closing of the throttle valve, the manifold vacuum is prevented from increasing as the throttle valve closes. Valve mechanism is thereby prevented from cycling and reopening the throttle valve.

When the foot pedal control rotates throttle lever 42 clockwise, lever 40 is rotated from tank 3S on lever 34, and the pressure of lever 34 against cam 5?; is relieved. A spring 76 engaging cam 58 rotates cam 5S in the counterclockwse direction. Cam 58 slips away from lever 34, returning to the position shown.

When the foot pedal control rotates throttle lever 42 counterclockwise, a tang 78 on throttle lever 42 engages a lever arm Si) of an inlet S2 mounted by a bracket 83 on carburetor 14, as shown in FIGURE l. Lever arm 86 closes a stopper valve 84, preventing atmosphere from passing through inlet S2 into hose 74 and permitting manifold Vacuum to build up. When the foot pedal control rotates throttle lever 42 clockwise, and tang 78 does not bear against lever arm Sil, stopper valve 84 is opened by a spring 86, admitting atmosphere through inlet 82 to hose 74 and reducing the manifold vacuum conveyed to chamber 114 in mechanism 10. Thus, as long as the throttle valve is opened by the foot pedal control through throttle lever 42, valve mechanism 10 is prevented from actuating. The importune actuation 0f valve mechanism 10 during low speed, light load engine operation is thereby prevented.

The construction of the alternative embodiment of valve mechanism 10 is shown in FIGURE 6. A housing 261i has a port 202. Hose 26 provides an air flow conduit between port 262 and the intake manifold of the engine.

Passages 268 and 21S provide an air llow conduit between port 202 and a chamber 220 formed between housing 26) and a exible diaphragm 222. A vent 224 admits atmosphere to chamber 226.

Manifold vacuum passes through port 202 and passages 238 and 21S, enters chamber 220 and combines with the atmosphere entering through vent 224 to produce a subatmospheric pressure in chamber 221i. The value of the subatmospheric pressure in chamber 226 may be regulated by the relative sizes of restrictions 226 and 22S located in passage 212 and vent 224, respectively.

A vent 231 maintains the chamber 236 behind diaphragm 222 at atmospheric pressure. The diierence in pressure on the two sides of diaphragm 222, atmospheric pressure in chamber 236 and subatmospheric pressure in chamber 220, tends to pull diaphragm 222 to the right against `the force of a spring 232 acting through a plunger 234 secured to diaphragm 222.

A bracket 236 secured to diaphragm 222 supports a gasket 23S. A spring 241D biases gasket 238 away from the end of plunger 234. When the manifold vacuum becomes suthciently high to overcome the force of spring 232, diaphragm 222 moves toward the right. Plunger 234 and spring 24) push gasket 238 over vent 224 and close vent 224. Therefore, atmosphere can no longer enter chamber 220 and the pressure therein reduces to manifold vacuum. This value of manifold vacuum in chamber 224i provides less resistance to movement of diaphragm 222 to the right, and conversely, tore resistance to movement of diaphragm 222 toward the left. Thus, the manifold vacuum existing when diaphragm 222 moves to the left being lower than that required to move diaphragm 222 to the right by a predetermined increment, a differ ential pressure diaphragm is provided which operates a valve as described below.

Threadedly received in the other end of plunger 234 is a stud 242 which bears against a spring 244. Spring 244 controls a valve 246 located within a passage 212.

Valve 246 is adapted to alternatively open either passage 214 or 249 to passage 212. A port 216 provides an air flow conduit between passage 214 and hose 16. A port 24S provides an air flow conduit between passage 249 and hose 18.

A vent 259 admits atmosphere to passages 214 and 249 through restrictions 251.

While diaphragm 222 and valve 246 remain in the position shown, manifold vacuum passes through port 202, passage 26S, a chamber 210 formed by the interior of housing 206, passages 212 and 214, port 216, and hose 16, enters servo mechanism 2@ and combines with the atmosphere entering through vent 250, passage 214, port 216, and hose 16 to create a subatmospheric pressure in servo mechanism 26. Servo mechanism 2() then causes distributor 24 to advance the spark.

Also, while diaphragm 222 and valve 246 remain in the position shown, atmosphere passes through vent 25), passage 249, port 248, and hose 18 and enters servo mechan-ismk 22 which then causes distributor 24 to ladvance the spar When high manifold vacuum causes diaphragm 222 to move to the right, stud 242 moves to the right and releases spring 244. Spring 244 forces valve 246 to the right, closing passage 214 and opening passage 249. Manifold vacuum passes through port 202, passage 20S, cham-ber 216, passages 212 and 249, port 248 and hose 18, enters servo mechanism 22 and combines with the atmosphere entering through vent 250, passage 249, port 248, and hose 13 to create a subatmospheric pressure in servo mechanism 22. Servo mechanism 22 then causes distributor 24 to retard the spark. Also, atmosphere passes through vent 259, passage 214, port 216, and hose 16 and enters servo mechanism 20 which then causes distributor 24 to retard the spark.

A valve mechanism is thus provided which supplies vacuum to servo mechanism 26 and atmosphere to servo mechanism 22 and advances the spark when manifold vacuum -is low and which supplies vacuum to servo mechan-ism 22 and atmosphere to servo mechanism 20 and retards the spark when manifold vacuum is high.

It will be appreciated that valve 246 and spring 244 might be replaced by other devices, such as a slide valve suitably connected to plunger 234, which would alternatively open either passage 214 or 249.

When valve 246 moves to the right, an air flow conduit is provided between a chamber 252 and port 202 through passages 254, 249, and 212, chamber 210, and passage 208. Chamber 252 is formed by clamping a flexible diaphragm 256 over the end of housing 206. A spring 258 biases diaphragm 256 toward the right, against the force of the throttle return spring (not shown).

Secured to diaphragm 256 is a plunger 260 in which is threadedly received a member 261. When diaphragm 256 is pulled by high manifold vacuum toward the right to the position indicated by outline 259, member 261 moves with it.

As illustrated in FIGURE 6, member 261 is slidably received through a slot 262 in a lever 264i fixed on a shaft 266 which controls the throttle valve 268. When mem- -ber 261 moves toward the right, lever 264 and shaft 266 are rotated clockwise, and throttle valve 268 opens. Slot 262 in lever 264 permits rotation of lever 264 by the normal foot pedal control (not shown) without interference from member 261.

It will be appreciated that the alternative embodiment of the differential pressure valve mechanism shown in FIGURE 6 and described above performs the same function as the valve mechanism disclosed in the aforementioned Bale patent. It will be further appreciated that the ball check valve, lever arrangement, and inlet mechanisms described above are easily connected to this 7 alternative embodiment and provide the same improvements with respect thereto.

Also disclosed in FIGURE 6 are means for preventing the valve mechanism from actuating in response to the high manifold vacuum created during a slight deceleration from high engine speeds. A passage 270, a chamber 272 and a vent 274 provide a conduit to admit atmosphere to chamber 220. Air ow between chamber 272 and passage 270 is normally interrupted by a diaphragm 276 biased by a spring 278 to seat across the opening of passage 270.

A hose 280, connected to the chamber 282 formed between housing 200 and diaphragm 276 and connected to the venturi nozzle 284 in an induction tube 286 of the carburetor 14, permits the application of venturi vacuum against diahpragm 275. At high speeds, when the venturi vacuum is high, diaphragm 276 will be moved upward from its seat across the opening -of passage 270, thereby allowing atmosphere to pass from chamber 272 through passage 270. The admission of atmosphere into chamber 220 prevents the s'ubatmospheric pressure therein from reaching the value at which the valve mechanism would actuate.

A valve 204 closed by a spring 206 is located in port 202 of housing 200, as shown in FIGURE 6. Valve 204 provides a substitute means of reducing cycling of the valve mechanism.

The operation of valve 204 is such that when the pressure differential across valve 204 is sufficient to overcome the force of spring 206, valve 204 opens and 4permits free air flow through port 202. When that pressure differential is not sufficient to overcome spring 206, valve 204 closes and acts as a restriction in port 202, permitting only limited air flow therethrough. Thus, when high manifold vacuum is created, valve 204 opens and permits air iiow through port 202, diaphragm 222 is pulled to the right, valve 246 opens passage 249, diaphragm 256 is pulled to the right, and throttle valve 268 is opened. The opening of throttle valve 268 reduces the manifold vacuum. Valve 204 then closes, thereby preventing rapid reduction of the vacuum within chambers 220 and 252. Air flow into these chambers is restricted to flow about valve 204 and ow through restriction 251. Such a flow delays the return of diaphragm 256 to the position shown and thereby delays the closure of throttle valve 268. T-he manifold vacuum is thus kept at a low value, and the cycling tendency is reduced.

It will be appreciated that although valve 204 sacrifices some efficiency in that it can only reduce cycling Whereas inlet 68 and the associated mechanism almost completely prevent cycling, valve 204 is a low cost device in comparison with inlet 68 and its required mechanism.

We claim:

1. A mechanism adapted to vreduce emission of unburned hydrocarbons from a decelerating engine which has a rotatable distributor and a throttle valve secured upon a rotatable shaft, said mechanism comprising a rst pressure responsive member, servo means, means to supply pressure to said member and servo means including valve means operable to regulate the pressure, said member being connectable to said throttle valve so as to open said throttle valve in response to a decrease in the pressure, said servo means being connectable to said distributor so as to retard the timing of said distributor in response to a decrease in the pressure, a second pressure responsive member to which manifold vacuum is supplied, said second member being connected to said valve means so as to operate said valve means to reduce the pressure supplied said first member and servo means in a predetermined range of manifold vacuum, inlet means adapted to supply atmosphere to said second member, stopper valve means closing said inlet means, and throttle lever means positioned about said shaft and adapted to drive said shaft in a throttle-opening direction, said throttle lever means being adapted to operatively contact said stopper valve 8 means upon closure of said throttle valve whereby atmosphere is supplied to said second member to reduce the vacuum and prevent said second member from cycling and otherwise importunely operating said valve means.

2. A mechanism adapted to reduce emission of unburned hydrocarbons from a decelerating engine which has a rotatable distributor and a throttle valve secured upon a rotatable shaft, said mechanism comprising a first pressure responsive member, servo means, means to supply pressure to said member and servo means including valve means operable to regulate the pressure, said member being connectable to said throttle valve so as to open said throttle valve in response to a decrease in the pressure, said servo means being connectable to said distributor so as to retard the timing of said distributor in response to a decrease in the pressure, a second pressure responsive member to which manifold vacuum is supplied, said second member being connected to said valve means so as to operate said valve means to reduce the pressure supplied said first member and servo means in a predetermined range of manifold vacuum, inlet means adapted to supply atmosphere to said second member, stopper valve means closing said inlet means, a throttle lever adapted to rotate said throttle valve, and a throttle lever positioned about said shaft and adapted to drive said shaft in a throttle-opening direction, said throttle lever being connected to said stopper valve means so as to open said stopper valve means upon opening of said throttle valve by said throttle lever whereby atmosphere is supplied to said member to reduce the vacuum and prevent said member from importunely operating said valve means.

3. A mechanism adapted to reduce emissions of unburne'd hydrocarbons from a decelerating engine which has a rotatable distributor and a throttle valve secured upon rotatable shaft, said mechanism comprising a first pressure responsive member, servo means, means to supply pressure to said member and s'ervo means including valve means operable to regulate the pressure, said member being connectable to said throttle valve so as to open said throttle valve in response to a decrease in the pressure, said servo means being connectable to said distributor so as to retard the timing of said distributor in response to a decrease in the pressure, a second pressure responsive member to which manifold vacuum is supplied, said second member being connected to said valve means so as to operate said valve means to reduce the pressure supplied said iirst member 4and servo means in a predetermined range of manifold vacuum, inlet means adapted to supply atmosphere to said second member, stopper valve means closing said inlet means, a throttle lever posi' tioned about said shaft and adapted to drive said shaft in a throttle-opening direction, and means movable into the path of said lever to open said stopper valve means upon Iclosure of said throttle valve by said first member whereby atmosphere is supplied to said second member to reduce the Vacuum and prevent said second member from cycling.

4. A mechanism adapted to reduce emission of unburned hydrocarbons from a decelerating engine which has a rotatable throttle valve and distributor, said mechanism comprising a pressure responsive diaphragm, servo mechanisms, means to supply air to said diaphragm and servo mechanisms including a first valve operable to regulate the air pressure, said diaphragm being connectable to said throttle valve so as to rotate said valve in response to a change in the air pressure, said servo mechanisms being connectable to said distributor so as to rotate said distributor in response to a change in the air pressure, a ball check valve adapted to regulate the rate of change of the air pressure supplied to said diaphragm whereby a sudden closure of said throttle valve by said diaphragm is prevented, a piston to which manifold vacuum is supplied, said piston being connected to said first valve so as to operate said valve in response to changes in manifold vacuum, an inlet adapted to supply atmosphere to said 9 piston, a stopper valve closing said inlet, a lever arm'con'- trolling said stopper valve, a throttle lever adapted to rotate said throttle valve, a tang extending from said throttle lever, said tang adapted to engage said lever arm so as to open said stopper valve upon opening of said throttle valve by said throttle lever whereby atmosphere is supplied to said piston to reduce the vacuum and prevent said piston from importunely operating said valve, a second inlet adapted to supply atmosphere to said piston, a second stopper valve closing said second inlet, a second lever arm controlling said second stopper valve, a cam, and a lever connected to said diaphragm and adapted to engage said cam and cause said cam to engage said second 10 lever arm so as to open said second stopper valve upon closure of said throttle valve by said diaphragm whereby atmosphere is supplied to said piston to reduce the vacuum and prevent said piston from cycling.

References Cited bythe Examiner UNITED STATES PATENTS 2,621,482 12/1952 Meade 123--103 X 2,782,025 2/1957 Olson 12S-103 X 3,027,884 4/1962 Bale et al 123--103 X MARK NEWMAN, Primary Examiner.

L. M. GOODRIDGE, Assistant Examiner. 

1. A MECHANISM ADAPTED TO REDUCE EMISSION OF UNBURNED HYDROCARBONS FORM A DECELERATING ENGING WHICH HAS A ROTATABLE DISTRIBUTOR AND A THROTTLE VALVE SECURED UPON A ROTATABLE SHAFT, SAID MECHANISM COMPRISING A FIRST PRESSURE RESPONSIVE MEMBER, SERVO MEANS, MEANS TO SUPPLY PRESSURE TO SAID MEMBER AND SERVO MEANS INCLUDING VALVE MEANS OPERABLE TO REGULATE THE PRESSURE, SAID MEMBER BEING CONNECTABLE TO SAID THROTTLE VALVE SO AS TO OPEN SAID THROTTLE VALVE IN RESPONSE TO A DECREASE IN THE PRESSURE, SAID SERVO MEANS BEING CONNECTABLE TO SAID DISTRIBUTOR SO AS TO RETARD THE TIMING OF SAID DISTRIBUTOR IN RESPONSE TO A DECREASE IN THE PRESSURE, A SECOND PRESSURE RESPONSIVE MEMBER TO WHIC MANIFOLD VACUUM IS SUPPLIED, SAID RECOND MEMBER BEING CONNECTED TO SAID VALVE MEANS SO AS TO OPERATE SAID VALVE MEANS TO REDUCE THE PRESSURE SUPPLIED SAID FIRST MEMBER AND SERVO MEANS IN A PREDETERMINED 